In conventional techniques, a configuration is employed in which, when picture data is displayed on a screen of a television receiver, for example, picture quality settings such as contrast and brightness are appropriately changed based on a state of screen display for the picture data displayed on the screen to be preferably viewed. A known example of the configuration for changing the picture quality settings is a control technique of appropriately changing settings automatically according to picture data (for example, see Patent Document 1 or Patent Document 2).
In a technique described in Patent Document 1, a scene having a dark picture is detected. In the detection, a video signal is amplified at high gain and clamped at black level, and then, is held outside a video region while integrated at the video region. Based on a result of the detection, the picture quality determined by brightness, contrast, color intensity, and the like is controlled such that, in the scene having a dark picture, the brightness is increased while the contrast is decreased to keep the maximum amplitude of the video signal constant or the color intensity is decreased.
In a technique described in Patent Document 2, the picture quality, which is determined by brightness, contrast, color intensity, sharpness, and the like set by a viewer, is stored in a recording unit of a control circuit for each type of programs. When a program of an identical type is viewed, the type of the program is detected from program information in the received signal, such as EPG data. A picture quality setting condition of the detected type of the program is read from the recording unit and the received signal is processed to have the set picture quality.
[Patent Document 1] JP 2000-78496 A (left column of page 4 to left column of page 5)
[Patent Document 2] JP 2002-158941 A (right column of page 3 to right column of page 6)